import Foundation
import UIKit
import VDSTokens
import Combine

/// A dropdown select is an expandable menu of predefined options that allows a customer to make a single selection.
@objc(VDSDatePicker)
open class DatePicker: EntryFieldBase, DatePickerViewControllerDelegate, UIPopoverPresentationControllerDelegate {
    //--------------------------------------------------
    // MARK: - Initializers
    //--------------------------------------------------
    required public init() {
        super.init(frame: .zero)
    }
    
    public override init(frame: CGRect) {
        super.init(frame: .zero)
    }
    
    public required init?(coder: NSCoder) {
        super.init(coder: coder)
    }
    
    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    /// A callback when the selected option changes. Passes parameters (option).
    open var onDateSelected: ((Date, DatePicker) -> Void)?
        
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    internal var minWidthDefault = 186.0
        
    internal var bottomStackView: UIStackView = {
        return UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.axis = .vertical
            $0.distribution = .fill
            $0.alignment = .top
            $0.spacing = VDSLayout.space2X
        }
    }()

    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    open var calendarIcon = Icon().with {
        $0.name = .calendar
        $0.size = .medium
    }
    
    open var selectedDate: Date? { didSet { setNeedsUpdate() } }
    
    open var calendarModel: CalendarModel = .init() { didSet { setNeedsUpdate() } }
    
    open override var value: String? {
        get { selectedDateLabel.text }
        set { }
    }
    
    open var selectedDateLabel = Label().with {
        $0.setContentCompressionResistancePriority(.required, for: .vertical)
        $0.textAlignment = .left
        $0.textStyle = .bodyLarge
        $0.lineBreakMode = .byCharWrapping
    }
    
    public enum DateFormat: String, CaseIterable, CustomStringConvertible {
        case shortNumeric
        case longAlphabetic
        case mediumNumeric
        case consiseNumeric
        
        public var format: String {
            switch self {
            case .shortNumeric: "MM/dd/yy"
            case .longAlphabetic: "MMMM d, yyyy"
            case .mediumNumeric: "MM/dd/yyyy"
            case .consiseNumeric: "M/d/yyyy"
            }
        }
        
        public var description: String {
            return format
        }
    }
    
    open var dateFormat: DateFormat = .shortNumeric { didSet{ setNeedsUpdate() } }

    //--------------------------------------------------
    // MARK: - Configuration Properties
    //--------------------------------------------------
    internal override var containerSize: CGSize { CGSize(width: minWidthDefault, height: 44) }

    //--------------------------------------------------
    // MARK: - Overrides
    //--------------------------------------------------
    
    /// Called once when a view is initialized and is used to Setup additional UI or other constants and configurations.
    open override func setup() {
        super.setup()

        fieldStackView.isAccessibilityElement = true
        fieldStackView.accessibilityLabel = "Date Picker"
        fieldStackView.accessibilityHint = "Double Tap to open"

        // setting color config
        selectedDateLabel.textColorConfiguration = primaryColorConfiguration.eraseToAnyColorable()
              
        // tap gesture
        fieldStackView
            .publisher(for: UITapGestureRecognizer())
            .sink { [weak self] _ in
                guard let self else { return }
                if self.isEnabled && !self.isReadOnly {
                    self.togglePicker()
                }
            }
            .store(in: &subscribers)
    }
    
    open override func getFieldContainer() -> UIView {
        // stackview for controls in EntryFieldBase.controlContainerView
        let controlStackView = UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.axis = .horizontal
            $0.spacing = VDSLayout.space3X
        }
        controlStackView.addArrangedSubview(calendarIcon)
        controlStackView.addArrangedSubview(selectedDateLabel)
        return controlStackView
    }
        
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        
        if let selectedDate {
            formatDate(selectedDate)
        }
        
        selectedDateLabel.surface = surface
        selectedDateLabel.isEnabled = isEnabled
        calendarIcon.color = iconColorConfiguration.getColor(self)
    }
    
    open override func updateAccessibility() {
        super.updateAccessibility()
        let label = "Date Picker, \(isReadOnly ? ", read only" : "")"
        if let errorText, showError {
            fieldStackView.accessibilityLabel = "\(label) ,error, \(errorText)"
        } else {
            fieldStackView.accessibilityLabel = label
        }
        fieldStackView.accessibilityHint = isReadOnly || !isEnabled ? "" : "Double tap to open."
        fieldStackView.accessibilityValue = value
    }
        
    /// Resets to default settings.
    open override func reset() {
        super.reset()
        selectedDateLabel.textStyle = .bodyLarge
    }
    
    internal func formatDate(_ date: Date) {
        let formatter = DateFormatter()
        formatter.dateFormat = dateFormat.format
        selectedDateLabel.text = formatter.string(from: date)
    }
    
    internal func togglePicker() {
        let calendarVC = DatePickerViewController(calendarModel, delegate: self)
        calendarVC.modalPresentationStyle = .popover
        calendarVC.selectedDate = selectedDate ?? Date()
        if let popoverController = calendarVC.popoverPresentationController {
            popoverController.delegate = self
            popoverController.sourceView = containerView
            popoverController.sourceRect = containerView.bounds
            popoverController.permittedArrowDirections = .up
        }
        if let viewController = UIApplication.topViewController() {
            viewController.present(calendarVC, animated: true, completion: nil)
        }
    }
    
    internal func didSelectDate(_ controller: DatePickerViewController, date: Date) {
        selectedDate = date
        controller.dismiss(animated: true)
        sendActions(for: .valueChanged)
    }
    
    public func adaptivePresentationStyle(for controller: UIPresentationController) -> UIModalPresentationStyle {
        return .none
    }
}